Bushing pocket with oil ports



A g- 9 K. K. PALUEV 2,647,939

BUSHING POCKET WITH on. PORTS Filed Feb. 3, 1951 Inventor: Konstantin KPaluev,

torney.

Patented Aug. 4, 1953 BUSHING POCKET WITH OIL PORTS Konstantin Paluev, Pittsfield, Mass., assignor to General Electric Company, a. corporation of New York Application February 3, 1951, Serial No. 209,278 1 Claim. (o1.174-1s) My invention relates to electrical transformers and more particularly to transformershaving removable terminal bushings.

The high voltage terminals of large transformers are provided with long bushings to insulate them from the transformer casing. These bushings are removable from the casing of the transformer so that they can be shipped separately from the casing to reduce the over-all dimensions of the transformer. ject through orifices in the transformer casing and the terminals are connected to the windings within the casing. Cover plates for the orifices are usually provided for attachment during shipment but there are periods before the cover plates are attached and after the cover plates are removed when moisture can enter the transformer. Such moisture is highly undesirable as it materially reduces the dielectric strength of the transformer insulation.

An object of my invention is to provide a means by which removable bushings may be assembled and disassembled from an hermetically sealed casing of a transformer without breaking the seal.

Another object of my invention is to provide pockets upon the inside casing of a transformer to seal permanently the bushing apertures of the casing.

According to my invention, the windings of a transformer are enclosed in a casing including a cover secured to the side wall of the casing in a gas tight connection. The transformer is provided with removable terminal structures including bushings through which terminals project. The lower portions of the bushings project through orifices in the casing and intermediate flanges projecting from the bushings are secured to the casing around the orifices. Insulating pockets are secured to the inside of the casing around the orifices and enclosing the ends of the terminal structure projecting within the casing to complete the seal of the casing. Pocket terminals which project through the walls of the pockets are electrically connected to the windings. Plug and socket connections are provided between the terminals of the removable terminal structure and the pocket terminals to complete electrical connection between the terminals and the windings without breaking the seal of the casing when the terminal structures are mounted thereupon.

For better understanding of my invention, reference is made to the following specification and the accompanying single figure drawing which is a sectional view of a transformer incorporating my invention.

These bushings pro- According to the drawing, the casing I of a fluid filled transformer is provided with a side wall 2 enclosing windings .3. A cover 4, of easing l secured by bolts or the like to side wall 2 in a gas tight connection, is provided with bushing apertures, one of which is shown in the drawing; The casing shown is the type wherein a gas space is provided at the top of the casing above the normal fluid level 4a to permit thermal ex. pansion of the fluid in the transformer. As is well known in the art, and as shown in U. S. Patents 1,671,492, Skinner, and 1,739,092, Rodman, appropriate filling and pressure relief means, respectively, may be provided for the casing. This apparatus is not shown here since it does not comprise a part of the present invention. A terminal 5 extends through a bushing 6 of insulation material with a portion 22 of terminal 5 extending below the end of bushing 6. When assembled to cover 4, bushing 6 extends through the bushing aperture. As shown, bushing 6 is provided with an intermediate flange 8 for attachment to cover 4 around the bushing aperture by bolts or the like to allow a portion of bushing 6 to project within casing l. A suitable sealing member 9 is interposed between cover 4 and flange 8 to provide a gas-tight seal therebetween so that the transformer liquid can be replaced by a gas during shipment to reduce the shipping weight and so that nitrogen, or other suitable gas, may be maintained within the gas space above the transformer liquid during operation as shown in U. S. Patent 1,671,492, Skinner.

Pocket Ill is provided with a conducting cylindrical portion I8 having a flange [8a secured around a bushing orifice in cover 4. A lower cylindrical insulating portion l9 of pocket I0 is secured to portion I8 as by applying suitable cement l4 to the mating surfaces. Portion I9 is formed of ceramic material. The level of fluid 4a in casing I is kept above the bottom of portion Hi to insure total immersion of the whole length of portion IS, a condition required by consideration of electrical stresses between portion l9 and portion 18, since portion 18 is electrically connected to casing l which is at ground potential when the transformer is in operation.

A valve 20 is provided upon an arm 20a pivoted upon the wall of cylindrical portion [8. Arm 26a is spring biased so that valve 20 closes an orifice in the wall when bushing 6 is disassembled from casing I A member 5a encasing member 5 and usually formed of stiff paper is provided with a shoulder 2| to engage arm 20a. When bushing 6 is assembled to cover 4, arm 20a is 3 rotated by shoulder 2| to allow valve 20 to uncover the orifice through bushing l8.

Terminal in this modification is provided with a projection 22 extending into a pocket end portion 23 to form a quickly detachable plug and socket connection. End portion 23 is fastened to portion I9 of pocket ID by applying cement l4 or similar adhesive means to the mating'surfaces and is electrically connected by a lead |-5 to the transformer winding 3. A valve 24 is biased by a valve spring 25 to close an orifice in pocket end portion 23 when bushing Sis-disassembled from casing I. MemberEais provided with a projection 26 adapted toengage valve 124 and to operate the valve'against spring 25 150 provide an opening in bushing electrode 23 when bushing B is assembled upon casing thereby to allow the level of liquid to rise in pocket Illa when casing l is filled. A stopcock 21 mounted upon cover 4 communicates out of pocket Illa 'to'allow' escape of air to the atmosphere as liquid flows into casing"! andtpocket-lfla.

While particular "embodiments of this inven- 'tion areillustrated and described, imodifications thereofwill occur tothose skilled inthe:art. I desire it'to be understood, therefore, that this invention is not to he limited to 'theparticular arrangements disclosed and :I intendin the-appended claim to cover all such modifications which do not depart from the spirit .and scope of thisapplication.

What I claim as :new'and desire to secure by Letters Patent of :the United States is:

In a container for high-voltage electrical apparatus having a removable terminal bushing with one'end thereof projecting intosaidhousing -and a bushing pocket within saidcontainer portadjacentthe opposite end thereof and above the normal insulating oil level in said container fer maintaining the insulating oil level in said bushing pocket-equal to the level in the rest of said container, a valve associated with each of said andzbeing spring-biased to the closed position, said valves having means associated therewith engaging said removable terminal bushing for opening said valves in response to tde insertion of said removable terminal into said bushing pocket.

KONSTANTIN K. 'PALUEV.

References Cited in the -file of this {patent UNITED 'STATES PATENTS Number Name 'Date 1,798,367 vBurnham, .l .Mar. 31, 1931 2,280,711 'Machlettet .941. on. Apr. 21, 1942 2,396,871 ,Meyerhans l -c-. Mar. 19, 1946 FOREIGN PATENTS Number "Country Date 346,604 "Great'Britain Apr. 16,1931 575,058 Great Britain Feb. 1,19% 

